Metabolic syndrome (Met.S) is a growing medical problem in industrialized countries and is diagnosed when three of the following factors are present: abdominal obesity, elevated serum triglycerides, low serum high density lipoprotein (HDL) concentration, elevated blood pressure, and elevated blood glucose. The syndrome is associated with insulin-resistance, impaired glucose control, atherogenic dyslipidemia, oxidative stress, and enhanced cardiovascular risk.
Insulin resistance, a characteristic feature of metabolic syndrome (MetS), is known to be associated with impaired glucose tolerance and impaired fasting glucose. Consumption of a meal that is high in readily available carbohydrates and fat causes postprandial increases in glycemia and lipidemia and markers of oxidative stress, inflammation and insulin resistance.
Hyperglycemia has been shown to impose cellular oxidative stress through the increased generation of endogenous reactive oxygen species (ROS) particularly in adipose tissue, both in vitro and in vivo. Increased ROS, in turn promotes inflammation by activating nuclear factor-kappaB (NF-κB) transcription complex resulting in the expression of a number of genes coding for pro-inflammatory cytokines.
Oxidative stress and inflammation are believed to play a critical role in the pathogenesis of several diseases including atherosclerosis and diabetes. Oxidative stress impairs glucose uptake in muscle and fat and decreases insulin secretion from β cells of the pancreas, resulting in prolonged hyperglycemia, increased glycation endproducts and endothelial dysfunction, all of which contribute to the development of atherosclerosis. Since insulin resistance presents before the development of diabetes, early intervention strategies designed to reduce insulin resistance and improve glucose control could ameliorate unfavorable effects on blood vessels and risk for micro- and macro-vascular disease. One possible approach for decreasing insulin resistance and improving glucose control is to enhance the anti-oxidant status of the body.
As described previously consumption of a meal that is high in readily available carbohydrates and fat results in a postprandial increase in markers of oxidative stress, inflammation and insulin resistance (See, Burton-Freeman et al. I, (Burton-Freeman B, Talbot J, Park E, Krishnankutty S, Edirisinghe I., Mol Nutr Food Res. 2012 Feb. 14. doi: 10.1002/mnfr.201100649. [Epub ahead of print] PubMed PMID: 22331646); Burton-Freeman et al. II, (Burton-Freeman B, Linares A, Hyson D, Kappagoda T., J Am Coll Nutr. 2010 February; 29(1):46-54); and Edirisinghe et al., (Edirisinghe I, Banaszewski K, Cappozzo J, Sandhya K, Ellis C L, Tadapaneni R, Kappagoda C T, Burton-Freeman B M., Br J Nutr. 2011 September; 106(6):913-22).). These changes are accentuated in states where insulin function is impaired such as in MetS (REF). It has been suggested that fruits and vegetables, particularly those with a higher polyphenolic content, have favorable effects on human health due to their ability to modulate oxidative and inflammatory stress in peripheral tissues (See, Rahman I., Nutr Rev. 2008 August; 66 Suppl 1:S42-5; and Rahman I, Biswas S K, Kirkham P A, Biochem Pharmacol. 2006 Nov. 30; 72(11):1439-52.). Grape seeds are a concentrated source of polyphenols and have received considerable attention for their antioxidant capacity and biological effects (See, Leifert W R, Abeywardena M Y, Nutr Res 2008; 28:729-37; Chis I C, Ungureanu M I, Marton A, Simedrea R, Muresan A, Postescu I D, Decea N., Diab Vasc Dis Res. 2009 July; 6(3):200-4; Meeprom A, Sompong W, Suwannaphet W, Yibchok-anun S, Adisakwattana S., Br J Nutr. 2011 October; 106(8):1173-81; and Kim Y, Choi Y, Ham H, Jeong H S, Lee J., J Med Food. 2012 Mar. 8. [Epub ahead of print] PubMed PMID: 22400909.).
There is a need for a method of modulating the oxidative stress, inflammation, and impaired insulin sensitivity in patients with metabolic syndrome (Met.S). Herein is provided a method comprising acute supplementation with grape seed extract (GSE) in the diet of a patient suffering from Met.S to improve antioxidant status and impaired insulin action following consumption of a pro-oxidative high carbohydrate, moderate fat meal.